Electric discharge apparatus



Nov. 13, 1934. E. D. M ARTHUR ELECTRIC DISCHARGE APPARATUS Filed May 21, 1931 Inventor: 0 Elmer D.TTlcArthu by W M Patented Nov. 13, 1934 PATENT OFFICE ELECTRIC DISCHARGE APPARATUS Elmer D. McArthur,

Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application May 21, 1931, Serial No. 539,038

4 Claims.

The present invention relates to electric discharge apparatus, and more particularly to transmitter tubes of the fluid cooled type designed to generate and amplify high frequency oscillations of considerable power.

In ultra short wave radio transmission, for example, when utilizing waves of the order of ten .meters or less, vacuum tubes containing a filament, an anode and an electrostatic control member are ordinarily employed to generate and amplify the high frequency oscillations. It is found that notwithstanding the care exercised in the design and manufacture of tubes of this sort, as known to the prior art, considerable unnecessary impedance still exists in the metal parts contained within the device, and more particularly in the conductors which supply current to the electrodes. This impedance which may be capacitative, inductive, or resistive, reduces the operating efhciency of the devices in the translation of the shortest waves useful in practice, and may if large, entirely prevent the generation or amplification of these waves.

A substantial portion of the impedance is found 5 toreside in the control member or grid lead structore, more especially in the region of the clamp which ordinarily secures the grid to a reentra-nt stem of the envelope. Moreover, the control electrode and leads of the prior art tubes, invariably contain a large and unnecessary number of mechanical joints which give rise to resistance, resulting in energy loss. While these factors may not be particularly undesirable in low frequency or small power devices, they are veryobjectionable in large power tubes which are called upon to translate frequencies of the shortest wave lengths, at maximum operating efliciencies and with loads of the order of several kilowatts or more. The presence of the various impedances in the interior of the tube renders the reactors, which ordinarily are provided in the external circuits to control the frequency of the generated or amplified waves, practically useless when these frequencies are of wave lengths as short as a few 5 meters.

The general object of the present invention is to provide an improved vacuum tube of the watercooled power type for use in high frequency circuits. In carrying out my invention, I find it expedient to apply the improved construction more especially to the control member of these tubes and accordingly, 9. more specific object of the invention is to provide an improved grid and associated lead structure for devices of the type men- 5 tioned. These objects are attained, in brief, by

discarding the usual grid clamp arrangement in favor of a construction in which the grid support is secured in a more direct manner to envelope than has heretofore been provided. The improved support takes the form of a pluno rality of parallelly connected rigid conductors, entirely separate from one another except at their terminations, saidconductors being made as short as possible and secured to the grid and its external terminal member with the mnnher of joints.

The invention will be better understood when reference is made to the following specification and the accompanying drawing in which Fig. 1 represents an elevational view, partly broken away in section, of a short wave transmitting tube improved in accordance with my invention; Fig. 2 is a cross-sectional view of the tube taken along line 2-2 of Fig. 1 and 3 is an enlarged view of the grid support and seal.

Referring to Fig. 1, numeral 1 designates the envelope of a highly evacuated tube, a portion of which constitutes an anode 2 and contains a helical filament 3, also a grid or control member 4. The anode is of the type adapted to be placed in a water jacket (not shown) on which it is supported by means of a collar 5. Fitted snugly within the anode, there is the usual sleeve 6 which protects the tapered seal 7 from electron bombardment. The filament 3 constitutes a tungsten helix supported at each end by a relatively heavy conductor 8 which iscarried through the top of the envelope and terminates in a flexible conductor 9. The conductors 9 may be held apart by insulating beads 10.

The grid helix 4 is supported between two circular plates 11, held together by four equidistantly spaced stay rods 12. The .grid as a whole, is rigidly mounted within the anode by means of several stiff wires 13, three as exemplified, which are secured at their lower end to the upper plate 11 and at their upper end, to the grid seal member 14. The wires 13 are entirely separate from one another except for the common end connections. The grid seal member is made in the form of a 10 metal cap with an extension, cut to a knife edge 15 for scaling to a transverse extension of the glass envelope. The cap is also provided with a closed tubular terminal portion 16 whose interior carries a threaded rod 17 on which a circular 1 5 plate member 18 is secured by a nut 19. The grid conductors 13 may be welded in holes bored in this plate member. These conductors are so arranged with respect to the adjacent filament conductors 8 as to leave as much space as possible 110 between them, thereby reducing the inter-lead capacity to a minimum. As exemplified in Fig. 2, the filament conductors are located in a plane parallel to the plane passing through two of the grid conductors.

It will be apparent from the drawing and the foregoing description, that the improved grid conductor arrangement utilizes single lengths of wire from terminal 16 to the grid proper, hence, involves the minimum number of joints, also the smallest amount of resistance, and eliminates the necessity of a grid clamp which invariably results in an increase of inter-electrode capacity. Lastly, by reason of utilizing at least three grid conductors connected in parallel, as straight as possible, and of the shortest length consistent with the position of the grid seal, the inductance of the lead structure as a whole is considerably reduced from that of the prior art devices. It will be understood that the prior art tubes of the .type described herein usually employ only a single conductor for the grid lead, or where more than one lead is provided, such leads are mechanically connected together at positions intermediate their lengths in order to provide a rigid support frame for the grid. It is apparent that in these prior art multi-grid-lead arrangements, the frame as a whole must be considered as a single conductor of largemetal content as far as the electrical properties of the grid are concerned and as such, fails to ofler a reduction of inductive impedance such as applicant's separate, parallelly connected conductors afiord. The advan tages of applicants improved construction are such as to lend the latter readily to power tube design in which oscillations of the highest frequencies are generated or amplified, without appreciable loss in efiiciency resulting from grid reactance, inductance and resistance.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. An'electron discharge device of the power type for translating frequencies of the order of a few meters, said device comprising an envelope formed partly of glass and partly of metal, the metal portion constituting the anode of the device, said envelope containing a cathode and a control member, a leading-in conductor for said cathode extending through the glass portion of the envelope, a terminal for said control member secured to the glass portion of the envelope, said terminal positioned intermediate the anode and the. position where the cathode leading-in conductor extends through the envelope, an integral conductor secured directly to the control member and terminating at said terminal.

' '2.- Anelectron discharge device of the 'power type for translating frequencies of wave lengths lessthan a few meters, said device comprising an envelope formed partly of glass, and partly of metal, said metal portion constituting an anode adapted to be cooled by a fluid, a filamentary cathode and an electrostatic control element contained within said anode, a pair of rigid conductors passing through the glass portion of the envelope for positioning the filament within the anode, a plurality of integral rigid conductors located adjacent the filament conductors and secured directly to the control element, the conductors being equidistantly spaced, said control element conductors terminating directly in a metal member secured to the exterior of said glass portion and being separate of one another except at their terminations.

3. An electron discharge device of the power type for translating frequencies of the order of a few meters, said device comprising an envelope formed partly of glass and partly of metal, the metal portion constituting the anode of the device, said envelope having a transverse extension of glass, a cathode extending through the glass portion of the envelope, and an electrostatic control element in said envelope, a leading-in conductor for said cathode, a terminal member for said control element secured to said transverse extension intermediate the anode and the position where the cathode leading-in conductor extends through the envelope, and a plurality of integral conductors connected directly between the control element and said terminal member, said conductors being substantially straight except for a bent portion necessitated by the position of the terminal member in the transverse extension of the envelope.

4. An electron discharge device of the power type for translating frequencies of the order of few meters, said device comprising an envelope formed partly of glass and partly of metal, said metal portion constituting the anode of the device, said envelope having a transverse extension of glass, a cathode and an electrostatic control element in said envelope, a leading-in conductor for said cathode extending through the glass portion of the envelope, a terminal member for said control element secured to said transverse extension intermediate the anode and the position where the cathode leading-in conductor extends through the envelope, and a plurality of integral conductors connected directly between the control element and said terminal member, said conductors being substantially straight except for a bent'portion necessitated by the position of the terminal member in the transverse extension of the envelope, said conductors being physically independent of one another except at their ends which are joined to the control element and the said terminal.

ELMER D. MCARTHUR.

(Seal).

CERTlFlCATE 0F CORRECTION Patent Not 1,980, 870. November 13, 1934.

ELMER D. McARTHUR.

- It is hereby certified that error tppelrs in the printed specification oi the lbove numbered patent requiring correction as follows: Page 2, lines 97 and 98,

claim 3, strike out the words "extending through the glass portion of the envelope," and insert the same after "cathode" and before the comma in line 100, of said claim; and that the raid Letter; Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and celled this 5th day of February, A. D. 1935.

Leslie Frazer Acting Commissioner of Pntentn.

CERTIFICATE OF CORRECTION Patent No. 1.980, 870. November 13, 1934.

ELMER D. McARTHUR.

- It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, lines 97 and 98, claim 3, strike out the words "extending through the glass portion of the envelope," and insert the same after "cathode" and before the comma in line 100, of said claim; and that the aaid Letters Patent ehould be read with this correction therein that the some may conform to the record of the case in the Patent Otiioe.

Signed and aealed this 5th day of February, A. D. 1935.

Leslie Frazer (Sell). Acting Commissioner of Patenta. 

